Oil cooler



W. R. RAMSAUR June 28, 1949.

OIL COOLER 4 Sheets-Sheet 2 Filed Dec.

3nventor M-SAUE,

attorney w. R. RAMSAUR OIL COOLER June 28, 1949.

4 Shet s-Sheet 5 Filed Dec. 15. 1944 Zhwentor Ware-e avMs/we,

attorney Patented June 28, 1949 OIL COOLER Walter R. Ramsaur, Los Angeles, Calif., assignor to The Garrett Corporation, Los Angeles, Calif.,

a corporation of California Application December 13, 1944, Serial No. 568,018

5 Claims.

at low temperatures the oil congeals in the cooler and it is necessary to thaw the oil before it can be circulated through the cooler. It has been customary to employ a jacket or muff entirely surrounding the cooler to provide for a circulation of hot oil from the engine for thawing out the cooler. However, with such a muff, providing a relatively unrestricted path for the flow of oil, it is possible for the oil to become so congealed under extremely low temperatures, as to develop high resistance to circulation through the muff, and this creates the problem of making the muff sufficiently heavy to avoid being ruptured under the high pressures which may be developed under such conditions. Workers in the art have therefore constantly sought to improve the thawing characteristics of such oil coolers.

With this general object in mind, the invention contemplates an improved arrangement in an oil cooler of a short bypass from. the cooler inlet to the cooler outlet, normally closed but adapted to open so as to maintain the flow when the inlet pressure exceeds a predetermined maximum, said bypass, in addition to its bypassing function, being adapted to function as a means for warming up and thawing congealed oil in the cooler core.

An important object of the invention is to reduce the weight of the cooler by eliminating the conventional warm up jacket or muff and employing an axially extending bypass to provide the warm up area. The reduction in weight results not only from the elimination of the weight of the muff, but also from elimination of the weight of the oil contained therein. To this end, the invention aims to provide a cooler wherein the warm up area is confined to the bypass, and in place of the conventional muff entirely surrounding the full area of the cooler, there is employed a pair of manifolds which provide, respectively, a passage from the main cooler inlet to the inlet port in the core and a passage from the core outlet to the main cooler outlet, and which are restricted to the area necessary to provide such passages.

More specifically, the invention contemplates .tubes 22. .prises air, may flow through the tubes 22 so as -to extract heat from the oil in the spaces 3| a cooler arrangement wherein a bypass, arranged in direct heat transfer relation to one side of the oil flow passage in the cooler core, substantially covers the entire area of the flow path on that side, thus employing the bypass rather than a muff as the primary means for providing a warm area covering substantially the full length of the flow path. The invention assures the transfer of heat for de-congealing purposes at all times when needed, even when the oil is bypassing directly from the inlet to the outlet.

Further objects and advantages of the invention Will be brought out in the following part of the specification.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a plan view of an aircraft oil cooler embodying the invention, with parts broken away to illustrate the interior structure thereof;

Fig. 2 is a side elevation of the same, likewise broken away to illustrate the interior structure;

Fig. 3 is a transverse sectional view of the same taken on the line 33 of Fig. 2;

Fig. 4 is a longitudinal sectional view of the same taken on the line 4-4 of Fig. 3;

Fig. 5 is a detailed transverse sectional view taken on the line 5-5 of Fig. 1 and showing a portion of the outlet passage;

Fig. 6 is a plan view of an oil cooler embodying a modified form of the invention; and

Fig. 7 is a transverse sectional view of the same taken on the line of Fig. 6.

As an example of one form in which the invention may be embodied, I have shown in Figs. 1 to 5 inclusive an oil cooler embodying a shell ll of tubular form, a radiator core l2 therein and a fitting l3 which incorporates an inlet I4 and an outlet [6, secured to the top of the shell in a position extending longitudinally thereof.

The radiator core l2 comprises a plurality of bundles of radiator tubes 22, and a plurality of bafiles 23, 24, 25, 26, 2'! and 28, separating the respective tube bundles. The tubes 22 are provided With expanded hexagonal ends 29 which are soldered together and to the intervening baffles 23-28 to provide continuous end walls in the respective ends of the cooler enclosing between them the longitudinal spaces 3| through which the oil may flow around and between the The coolant, which ordinarily comthrough the Walls of the tubes, in the normal operation of the cooler.

The baffles 2328 are corrugated as indicated This tortuous path is indicated by the arrows 43- in Fig. 4.

The fitting I3 is attached to a mating fitting 44 by means of bolts 46, the fitting-4min turn being welded to the shell H andwooperating with a sheet metal jacket member I! which also is welded to the shell H.

from a port 59 in the left side of the fitting M (as viewed in Fig.3) to-the inlet port lii'in-theshell IL- The jacket member ll'further includes a longitudinal arm 5| which is welded 'totheshell I l at one side thereof and to the fitting when its other side to form, together with the shell "I I and the fittingiMjthe main portion 52 of the bypass passage and Warm up-chamber. From the portion 52; the bypass-is'continued through a port 53-in-theleftsideof thefitting Mras viewed inv The jacket member I! 3 includes a circumferential arm 41 which cooperates with the shell to define an inlet passage 48 extending Fig;- 3) into-a bypass valve chamber 54: in the fitting l3 and thence throughaportfifi into the 'outlet'chamber 51in the fitting 13; Between the port'53 and-thechamber 54= is a-valve port 58 which is normally closed by a valve=i59- under the yieldingpressure-flof a spring-60." The portion 52 of the bypass is substantially: coextensive in length with the "fittingso as to provide-a warm .up

chamber=eXtending-.-the full length of the-oil circulation spaces-fil, but-the left-end of the portion 52- is separated frorn the outletchamber 51 by the left wall-55- 'of-thelatter (as-'viewed'in Fig. 5) which extends'totheshell 'll.- Thus the leftend of the space 52 forms-a pockettl'win which the bypassing oil may; circulate, but from which it must return to the' -port' 53 in its path through the bypass.

An outletchannel' lfi is welded to theshell II" and to the fitting 44 jto provide; an outlet passage fil extending from the outlet port 21 to the chamher 5] through a; port; 6 2in1the-right" hand side ofthe fitting a4" (as viewed in rig. 5

The internal construction of the' fittings l3 and 4411s, substantially the same as that disclosed in my earlier application, v Serial No.' 383,731, filed March 1'7, 199:1,,for Letters Patent on a High capacity oil cooler, and reference; ismade to that,

application for-amorecomplete showing of such construction;

In accordance with the'present invention; the

edges join'the shelll [in an area extending'longitud'inally of the cooler and somewhatirestricted circumferentially, so that said; area may corre- 5 [and extending from end to end" of; the fitting 44; As shown in Fig. 3-, this warm up areacovers' one side of allof the compartments314l inclusive of the core flow path, 'onlythe =terminalcompartments 36 and 42 being excluded] from the ov ra by gwarm up a e' er trernities'of these latter compartments will; howof the bypass; asa warm up space, may beconsidered'to 'include all of 'the' 2 the inlet ciency the 'core forthe provision of an oil flow path ever, be heated by conduction from the immediately adjacent warm up area. In order that the upper extremities of the compartments 3'l-4l may be properly related in this manner to the warm up area, the baffles 23-468 are spaced more closely together in the central region of the cooler than at the sides and are inclined so as to subtend asmall dihedral angle withlreference to the axial vertical plane of the cooler passing through 14 and outlet IS. The progressively wider spacing of the baffles from the center toward thesides also has the effect of rendering the cross sectional area of the compartments 3642 substantially uniform so as to obtain maximum effiof utilization of the available space within adapted-to handlea maximum flow of oil.

Due to the close association of the upper side of the oil fiow path with the warm up area throughout substantially its entire length, the initial now of hot oil through,the'bypass ingia congealed cooler will :quickly, thaw theoil in the upper regions, ofv the compartmentsfiS-dl so as to provide an initial. de-congealing oil flow pathrthroughout the majorportionof the length of the main oil flow path. Access ,to this decongealing path. fromthe inlet M may be providedby the flowing ofqthe oil in the passagel8;.; down to the inlet port [8; whichwill be effected; quite rapidly due to thefairly large, cross sectional area of the passage .48: However, theinventlQ i,

contemplates speeding. up the openingtofta path from the inlet 14 torthede-congealing path by providing substantially immediateaccess to the r de-congealing path from; the-bypass. To this,

end, 1 provide a plurality of bleed (ports, to, 61, as,

69,- lil, and ill in the,- shell I I, arranged generally, in-qa, line extendingfrom ,withinuthe-bypass to a point-near-the inlet port, 18,; To further facilitate:

opening the-de-congealing path, for the initialfiow-of'oiltherethrougn-a bleed-port, or ports,

12; may beincorporated in. the shell II in cornmunicationwiththe outlet passage 61 nearlthe;

port 62 so as toprovide a direct-outlet'fr omthe extreme upper extremity of the compartment 42.;

into: the outlet chamben 5'};

In the operation 0f -the=, cooler, thenormahflow;

is from the inlet ld'through the port 49- intothe, inlet passage, as: indicated-by the dot: and dash linei6, theme in. thetortuous flow. path 43;; through thecompartments- 35; 31-, 38;: 39; 40;; 4'13:

and 42% in the order named; withinthe radiator core then throughtheputletport, 2 I the outlet;

passage 6|, the portr62, the outlet-chamber 51' in-the, fitting l3; and -to,the outlet l6, as indi-- catedby, thedot and;dash.arrows-,zlfl, During its zigzag fiowthroughthepath:4 3;;within the radiator, core, theaoilis cooled by thecabsorptionof heat: therefrom through the;walls of; theatubes; 22";

bya coolant, suchas.air,-.passing-throughthe, tubes 22 from end to end of the cooler;

When the; oil is, thusfreely circulating through. the cooler, the bypassvalve- 59iwill remain closed:

under the pressure of the spring 60. 1 When the oilin the: cooler hasv become congealed, however, the initial flow. of hotv oil from the engine."

will. because of the resistance ofiered by the normal flow path build:- up a pressure in. the

bypass sufiicient to raise thevalve- 591'and permit the oil to bypass: directlyto-the outlet [6' through the bypass, as indicated bythe heavy arrows 758. In order to divert the bypass-flow as much as possible into the dead endwarrning e s? 5. h r s sro id gn g te h a t a pair'of deflector members 19 and Bi which may be strips of angle iron welded to the shell ll. This flow of hot oil through the bypass will quickly warm the area of the shell ll immediately over the upper side of the tortuous flow path 43 so as to thaw the oil in said path immediately adjacent the shell ll. At the same time, the pressure built up in the bypassing oil by the resistance of the spring Gil will urge the hot oil to pass through the bleed port 66 into the beginning end of the de-congealing path (the upper region of the compartment 36). through the bleed port 66 will cause the shallow body of Clo-congealed oil in the initial flow path to start flowing to the outlet bleed ports 12 and thence to the outlet l6, thus establishing an initial small volume circulation of thawed oil in the initial flow path. This initial circulation of oil will exert a sluicing action against the deeper layers of congealed oil in the main flow path 43, gradually deepening the opened portion of the flow path. At the same time the thawing action in the bypass will spread downwardly into the inlet passage 48 and toward the inlet port I B, successively opening the bleed ports 61, 68, 63, 10, and 1!. As each of these ports is successively uncovered, the circulation of oil through the initial flow path will be speeded up and the pressure in the bypass will be gradually lowered. In response to this lowering pressure the valve 59 will move toward its closed position, gradually throttling off the bypass flow in proportion to the increased flow through the core. Thus the thawing out will be accelerated until the congealed oil is completely thawed and sluiced out of the radiator core. the bypass closed off by the valve 55%, and the full normal flow from the inlet port IE to the outlet port BI is established.

In the alternative form of the invention, shown in Figs. 6 and 7, the principles of arrangement and construction described above are embodied, and the same reference numerals are used to designate the same, with the exception of the arrangement of the baflles 23a, 24a, 25a, 26a, 21a, and 23a in symmetrical relation to the vertical axial plane of the cooler passing through the inlet and outlet openings Bi and B2 (of the fitting 44) and the restriction of the bypass area to substantially the area of the fitting 44, the longitudinal arm 5m of the muff Ho, being just sufficiently large to establish the bypass flow between the inlet opening BI and the bypass valve port 56a. The upper extremities of the flow compartments 36a, 37a, 38a, 33a its, lla and 42a are narrowed down so that all except the terminal compartments 36a and 4211 are covered by the fitting 44 and thus in direct heat transfer association with the warm up bypass area. In order to make this possible, and at the same time to properly distribute the cross sectional area of the cooler core between these compartments so that the cross sectional area of all compartments may be substantially uniform, the outer pairs of baliies 23a, 28a, and 24a, 21a, respectively are offset as at 83 and 84 respectively from the plane of symmetry of the entire group of baflies, thus widening the compartments 36a, 31a, 38a, Ma, Ma, and 42a in their lower regions.

At this point it may be noted that, for the purpose of clarity and detailed showing of the tubes 22, they are illustrated in much larger proportion to the size of the cooler than the actual proportions employed in the construction of coolers in accordance with the invention. For example, in the central compartment as of Figs. 3 and 4, only two tiers of tubes are shown, whereas The oil thus flowing in actual practice four or five of such tiers may be employed, as shown in Fig. 5. One of these tiers, for example, a tier adjacent one of the baffies, may, by use of spacing strips 86 and 81, be spaced from the bafile and from the adjacent tier of tubes by oil flow spaces am and 3!!) respectively, which are wider than the rest of the oil flow spaces 3| so as to facilitate the sluicing action of the hot oil in the initial de-congealing flow path, and speed up the clearing of the remainder of the normal flow paths. The strips BS and 81 are soldered between the hexagonal tube ends and between the latter and the battles respectively. In a similar manner, the extremities of the compartments 35-42 adjacent the shell ll may be provided with enlarged flow spaces 340, Fig. 3, between the tubes 22 and the shell ll, through the use of a spacer ring 88 between the shell and the hexagonal tube ends, and short semi-hexagonal filler plugs 89 interposed between the ring 88 and alternate hexagonal heads 29.

I claim as my invention:

1. An oil cooler comprising a shell, a radiator core within said shell comprising tubes extending longitudinally of said shell, inlet and outlet ports in said shell, baflles extending longitudinally of said shell in spaced side by side relationship dividing said cooler into parallel longitudinally extending compartments, there being communi= eating openings between said compartments adjacent the ends of said baiiles and adjacent said shell, said openings being disposed alternately at opposite ends of the cooler to form a tortuous oil flow channel from said inlet port back and forth longitudinally of said core to said outlet port with at least one side edge of said channel being formed by the interior surface of said shell, walls cooperating with the exterior surface of said shell to define a chamber exteriorly of said shell provided with a cooler inlet in communication with said inlet port and a cooler outlet in communication with said outlet port, said chamber forming a bypass exteriorly of said shell which extends from said cooler inlet to said cooler outlet and being of such extent peripherally of said shell as to substantially overlie one side edge only of each of said bailles to concentrate the transfer of heat from hot oil flowing through said bypass to one side edge only of said oil flow channel to rapidly decongeal oil along said one side edge of said fiow channel.

2. An oil cooler as defined in claim 1 having a valve which closes said bypass when resistance to flow of oil through said core is reduced to a predetermined value.

3. An oil cooler comprising a shell, a radiator core within said shell comprising tubes extending longitudinally of said shell, inlet and outlet ports in said shell, baflies extending longitudinally of said shell in spaced side by side relationship dividing said cooler into parallel longitudinally extending compartments, there being communicating openings between said compartments adjacent the ends of said bailles and adjacent said shell, said openings being disposed alternately at opposite ends of the cooler to form a tortuous oil flow channel from said inlet port back and forth longitudinally of said core to said outlet port with at least one side edge of said channel being formed by the interior surface of said shell, walls defining a chamber exteriorly of said shell provided with a cooler inlet in communication with said inlet port and a cooler outlet in communication with said outlet port, said chamber outletzand .--being 'of such extent peripherally of said shell' as to substantiallmoyerlie one side edge;

only of each of said baffles to concentrate the transferiof heat from hot oilcfiowing-through said chamber to one side edge;\ only of said oil flow channel to rapidly decongeal, oil along said one side, edge of said flow channel. j

An oil cooler compr s1ng a shell, a radiatorcore I Within said shell comprising tubes extendingylongitudinally 0t said shelLinlet andoutlet ports; ii -said shell, baffles extending longitudinally 'of said shell in spaced side by side relationship dividing said cooler into parallel longitudiv 15. munica-ting openings between said compartments nallyextending compartments, there being: comadjacent the ends of said baiiles andadjlacent said shell, said openings being disposed alternatelyat opposite ends. of the6 cooler toforma; tortuous oil-flow channelifromg said, inlet port, back. and: forth longitudinallyrof saidcore tosaid outlet port with at least one side edge. of said channel being formed by ltherinteriorl surface of said shell, a jacket extending longitudinally of the exterior of said shell"; and. being of such: eX- tent peripherallyof said shell as to substantially,

overlie one side ed e onlye-ofeach of said baflles,

saiddacket beinglprovided with a cooler inlet in,

communication with saidinlet-pQrt-and a cooler,

outlet in communication 1 with said; outlet port,

saidjacket forming with said-shell a bypassexe teriorly of said shellwhich extends 1on itu dinal-..

1y-i-of the cooler from said? cooler inlet-to said cooler outlet-in substantially overlying relationship to one sideedge only: of said oil flow channel-y to concentrate the transferof-;- heat-from hot oil' flowing through said bypass to said one side edge 1' only of said oil fiow channel to rapidlydecongeal oil along said one sideedge :of said fiow channel;

5, Anoilcooler comprising- -a' shell, a radiator core within said shell, inlet and, outlet'ports in; said shell baffles extendinglongitudinally; of said: shell in spaced side by]side relationshipdividing said cooler into parallel longitudinally; extending endsiotthe cooler :toa formla tortuous oil fflow compartments, there; being comrnunicating;open;

ingslbtween said compartments adjacent th endsaofisaid baffles and adjacent said she11,sa1 openings being disposedalternately the opposi channel from said inlet port I back. and forthlone,

gitudinallyk of .saidcore tosaid outlet portwith-a at least i one. 1 side edge of said channel being formed-by the interior surface-of said shell, wallsl l cooperating with the exterior surface of said shell to define arch-amber exteriorly of said shell, Walls} forming an oil cooler inlet through which oil may; flow to said chamber; and tosaid inlet :port and forming an oil cooler;- outlet through which-oil= .may ,flow-,from said chamber and .from said out let port, a deflector-positioned in said chamber around Which hot oil must: flow in passing through said J chamber, said chamber being oi such extent peripherally of said shell as to sub-,4

stantially -overlie one sideedge onlywof each ot said baffles to concentrate the. transfer of heat-:. from-oil flowing through said bypass to one sideedge only of said-oil flowchannel to rapidly de-.

congeal oil alongsaid-ioneside edge of said fiowa channel.-

WALTER R. RAMSAUR.

REFERENCES CITED The following referenlces are of record in the file 'of this patent:

UNITED STATES PATENTS 

